1. Field of the Invention
This invention pertains to an auger type gravel pack screen assembly adapted to produce fluids from a well in an earth formation from separate and isolated gravel packed zones by installing a substantially impermeable layer of gravel between the zones or by injecting a substance into a layer of gravel between the zones to reduce gravel permeability.
2. Background
Multiple gravel pack type well completions are sometimes desired for producing subterranean fluids from spaced apart zones in an earth formation. U.S. Pat. 5,145,004 to H. Mitchell Cornette and assigned to the assignee of this invention describes one arrangement for producing hydrocarbon fluids from multiple zones utilizing gravel packed wells with auger type gravel pack screens inserted therein. In some applications of gravel packed wells, however, the expense associated with the type of multiple completion described in the '004 patent is not justified or the space between the production zones is too short to utilize the type of apparatus required in the completion arrangement described in the '004 patent.
In certain wells which are capable of producing fluids from multiple spaced-apart zones, intermediate layers of formation material tend to produce water and/or gas which is unwanted when producing crude oil, for example, from the formation zones on each side of the water- or gas-producing zone. Moreover, one or the other of two spaced apart production zones may begin to produce unwanted quantities of water and/or gas. The flow of water and/or gas into an oil production well or water into a gas production well creates several problems such as, in the case of water incursion, requiring artificial lift, development of corrosion of the well structures due to mixing of oil with acidic gases and reduction in the production rate of the desired fluids. Producing gas into a well which is adapted to produce hydrocarbon liquids can also cause similar problems, as well as requiring certain separation and treatment equipment at the surface. Such problems result in lost reserves or require expensive remedial action.
Prior efforts to prevent production of water or gas from an earth formation zone which is intermediate gravel packed oil or gas production zones have not been successful. Plugging of part of the sand control screen or injection of cement to control the water and gas flow have been substantially unsuccessful, particularly when employing so-called auger type gravel pack or sand control screens. However, the present invention overcomes the disadvantages associated with prior efforts to produce fluids from multiple gravel packed zones or zones in which the boundary regions of the zone may be flooded by gas or water. The invention also solves problems associated with efforts to isolate spaced-apart production zones in a gravel packed well, particularly a well which utilizes an auger type gravel pack screen assembly.